There have been considerable advancements in the airbag art in recent years. One field that has received attention is the protection of occupant legs by the use of knee airbags. One approach to the use of such airbags has been to house them in an instrument panel assembly, in generally opposing facing relationship with the legs of an occupant. Examples of such configurations are illustrated in U.S. Pat. No. 6,715,789 and U.S. Pat. No. 7,434,837, incorporated by reference.
Recent developments in automotive vehicle design have created the need to re-locate knee airbag housings from a location generally contiguous with a occupant facing surface of an instrument panel to a location at the bottom of the instrument panel. For example, one desired approach is to design a vehicle cabin so that any knee airbag housing is located beneath the instrument panel, or so that the housing (which may thus avoid the need for a decorative cover) has a downward facing opening through which the airbag inflates.
Due to the large forces to which airbags are subjected during inflation there is a tendency, regardless of their structural configuration, for such airbags to inflate directly outward. For instance, during inflation, it is possible that substantially the entire volume of the airbag will be subjected simultaneously to substantially the same internal gas pressure.
Efforts to directionally control inflation have been unsuccessful in the absence of complicated structural arrangements. For example, in order to meet the need for wrapping upwardly and around the instrument panel, efforts have been made to incorporate a control element that connects the airbag to the airbag housing (such as by a rod fastening element), such as shown in Published U.S. Patent Application No. 2007/0246920, incorporated by reference. Another approach has been to include a structural blocking member opposite the airbag housing, against which the airbag contacts and deflects during inflation, which thus directionally guides the airbag as it inflates. For example, Published U.S. Patent Application No. 2007/0246920, incorporated by reference, illustrates the use of guidance hardware in the form of a horizontal housing bottom that subjects the bag to an “upwardly directed impulse”. Such approaches require the presence of additional components that potentially add weight to a vehicle, add assembly steps, or both, thus affecting cost or attractiveness of the devices for various applications. Another illustration of an approach to airbag deployment is shown in DE 19946477A1, incorporated by reference.
It would be beneficial to have an improved wrap-around airbag device. For example, it would be beneficial to have an airbag device such as a knee airbag device, that could inflate through a downward facing opening. It would be especially beneficial if such an improved knee airbag device could wrap upwardly and around an instrument panel. It also would be especially beneficial if such an improved knee airbag device could avoid the need for guidance hardware or other structural arrangement located external of the bag for directionally controlling inflation.